Chloro(2-chlorovinyl)alkylboranes and their preparation



P. R. KIPPUR 3,04

CHLORO zwmoaovmm ALKYLBORANES AND THEIR PREPARATION July 17, 1962 Filed Jan. 28, 1959 Perry R. Kippur INVENTOR.

ATTORNEYS United States Patent Orifice 3 045,044 CHLORO(Z-CHLORCVINYEJALKYLBORANES AND THEIR PREPARATION Perry R. Kippur, Hamden, Cnn., assignor to Olin This invention relates to' the preparation of chloro (2-chlorovinyl) alkylbor-anes. I

By the process of this invention, ch1oro(2-chlorovinyl) alkylboranes wherein the alkyl group contains 1 to carbon atoms are obtained by contacting activated carbon with acetylene and an alkyldichloroborane, wherein the alkyl group contains 1 to 5 carbon atoms. Suitable alkyldichloroboranes, such as .methyldichloroborane, ethyldichloroborane, n-propyldichloroborane, isopropyldichloroborane, n-butyldichloroborane, and n-amyldichloroborane, can be prepared according to the method described by Booth and Kraus in J. Am. Chem. Soc, volume 74, pages 1415-1417 (1952 which takes place when this process is carried out with ethyldichloroborane can be represented by the following equation:

The reaction temperature can be varied Widely from about 40 to about 115 C., while the preferred temperature range is from 60105 C. Temperatures above 115 C. must be avoided since at these temperatures ch1oro(2-chlorovinyl)ethylborane, for example, disprop'ortionates to give equirnolar quantities of ethyldichloroborane and bis-(2-chlorovinyl)ethylborane. In a like manner, the molar ratio of acetylene to alkyldichloroborane can also be varied through a wide range of from about 0.3 :1 to 1, preferably 0.5 :1 to 3:1. The activated carbon utilized can be derived from, for example, Wood, peat, lignite, nut shells, bones and so forth.

Chloro(2-chlorovinylalkylboranes are useful chemical compounds in that they can be converted to dialkylchloroboranes as described in the application of Clark et 211.,

Serial Number 789,742, filed of even date herewith and entitled Manufacture. Thus according to Serial No. 789,- 742, a chloro(Z-chlorovinylalkylborane is hydrogenated with molecular hydrogen in the presence of a palladium catalyst at a temperature of from 20 to 160 C. and at a pressure of from O p.s.i. g. to 50 p.s.i.g. to form the corresponding ethylalkylchloroborane. Application Serial No. 789,742 further discloses reaction of an ethylalkylchloroborane with tris(2-chlorovinyl)borane to form the corresponding (2-ch1orovinyl) ethylalkylborane which in turn can be hydrogenated according to the method described in Serial Ni). 789,742 to produce a diethylalkylborane. The latter trialkylboranes can be utilized to prepare diborane as described in Klein et a1. application Serial No. 614,768, now U.S. Patent 2,946,664. The following examples illustrate in detail the method of the invention.

EXAMPLE 1 The apparatus employed in this example is shown in FIGURE 1. It consisted of a stainless steel ethyldiohloro borane reservoir 1 of 200 cc. capacity connected at the bottom by means of line 2 to a. saturator vessel 3 which had a capacity of about 100 cc. saturator vessel 3 was equipped with a dip leg 4 through which acetylene was ledinto the saturator by means of line 5 containing rotameter 6. Inlets 7 and 8 for the introduction of nitrogen fromline 9 into the top of reservoir 1 and into line 5 to saturator 3 respectively were also provided. Reactor 10 which was aglas-s tube 30 inches in length and 1 inch (l.D.) containing a sinter'ed gass disk as a catalyst sup port, was provided with a jacketed section 11 about 24 inches in length for heating or cooling asidesired. The upper or inlet end of reactor it was connected to saturator 3 by line 12 While the outlet of reactor 10 was connected to a 500 cc. glass collection flask 13 by line 14. Also connected to line 14 by line 15 Was attached a cold finger type condenser 16 having a vent 17 and a hollow space 18 into which was placed a Dry Ice-acetone mixture at -78 C. The condenser was arranged in such a manner The chemical reaction that condensate leaving the condenser flowed downward- 1y into collection flask 13.

In this experiment, the reactor was charged with 150 cc. of activated carbon of 46 mesh size. A weighed quantity of ethyldichloroborane was charged to reservoir 1 in a dry box. The reactor system was assembled as shown in FIGURE 1 and after the catalyst bed had been heated to a temperature of 100 C. .by introducing steam into the reactor jacket, nitrogen was passed through the bed for a period of sevenal hours in order to remove absorbed Water from the carbon. The flow of nitrogen was stopped and acetyleneat the rate of 50 cc./min. at S.T.P. (.00223 mole/min.) was passed by way of line 5 and dip leg 4 into saturator 3 while ethyldichloroborane was passed by way of line 2 to the saturator at the rate of .00149 mole/ min. The temperature of heating jacket 11 was maintained at 100 C. As soon as the carbon had been completely saturated, liquid product consisting of ch1oro(2- chlorovinyl)ethylborane and unconverted ethyldichloro- 'borane was obtained. Non-condensible gases were vented through vent 17. After 13 hours, the flow of reactants was stopped, vent 17 was connected to a bubble-off, and the entire system placed under a positive pressure of nirtrogen.

The crude product, which collected in the product receiver, was analyzed by infrared and by elemental analysis. In this experiment, the average percent conversion to ch1oro(2-chlorovinyl)ethylborane was 75 percent and the percent yield was greater than 90.

Pure chloro(2-chlorovinyl)ethylborane can be recovered from the crude product by means of vacuum distillation carried out under a pressure of not over 35 mm. of mercury absolute. Since the product is pyrophoric,

- nitrogen should be used to control and relieve the vacuum in this distillation operation.

EXAMPLES 2'-6 substituted for the saturator and the acetylene inlet line was attached directly to the top of the reactor. With this exception, the apparatus employed in Examples 2-6 and p I 3,045,044 1 Patented July 17,1962

spams-a the method of operation were the same as that described are in contact with a catalyst consisting essentially of actiin Example 1. vated carbon.

Table 1 Jacket Mole, Mole Rate Total Av. Per- Example Temp., Catalyst CzHz/ Ratio, CzHz, hours percent cent 0. VOL, cc. min. Cz aiclzl cc./Inin. oi Run Conv. Yield CzHz Nora-In Example 6, the low yield is due to disproportionation of chloro(2-cl1lor0- vinyl)ethylborane to give equimolar quantities of ethyldichloroborane and bis(2-chl0roviny1)ethylborane. This disproportionation occurs at a temperature above about 115 0. Therefore, 115 C. is the practical temperature limit for carrying out this reaction.

It is claimed: 4. The method of claim 3 wherein the molar ratio of 1. Chloro(2-ch1orovinyl) alkylboranes of the formula acetylene to alkyldichloroborane introduced into the reaction zone is within the range from 0.3 :1 to :1.

(C1CHZCH)RBC1 5. The method of claim3 wherein the alkyldichlorobowherein R is an alkyl group containing from 1 to 5 carbon fang i h ldi mo bo ne, at 6. The method of claim 5 wherein the molar ratio of 2. Chloro(2-chlorovinyl) ethylborane 0f the formula acetylene to dichloroethylborane introduced into the reac- (ClCI-I CH)(C H )BC1 tion zone is within the range from 0.5:1 to 3:1.

3. A method for the preparation of chloro(2-chlorovi- References Cited in the file of this pawnt nyl)alkylboranes which comprises reacting acetylene and an alkyldichloroborane wherein the alkyl group contains UNITED STATES PATENTS from 1 to 5 carbon atoms at a temperature within the 2,402,589 Arnold June 25, 1946 range from about to about C. while the reactants 30 D STATES PATENT OFFICE OF CORRECTION July 17, 1962 UNITE CERTIFICATE Patent No 3.045044 Perry R. Kippur rtified that error appears in the above numbered pataid Letters Patent should read as It is hereby ce tion and that the s ent requiring correc corrected below.

inylalkylboranes" Column 1. n 40 for "Chloro(2-ch1orov read Ch1oro(2ch1orovinyl)alkylboranes 1ine45, for

ch1oro(2ch1or0viny1) "chloro(2chlor0vinylalkylborane" rea alkylborane line 64, for "200 cc." read 2000 cc.

Signed and sealed this 20th day of November 1962.

(SEAL) Attest: ERNEST W SW IDER AVID L. LA D Commissioner of Patents Attesting Officer 

1. CHLORO(2-CHLOROVINYL) ALKYLBORANES OF THE FORMULA 